Donald Trump picks outspoken Lt Gen McMaster as new national security advisor

US President Donald Trump on Monday named Lieutenant General Herbert Raymond McMaster as his new national security adviser, choosing a military officer known for speaking his mind and challenging his superiors.

"He is highly respected by everybody in the military and we're very honoured to have him," Trump told reporters in West Palm Beach where he spent the weekend. "He's a man of tremendous talent and tremendous experience."

A lieutenant general with the US Army, HR McMaster served in Iraq and Afghanistan, where he worked on a government anti-corruption drive.

The 54-year-old is know for his criticism of the US military's handling of Vietnam War and his own service as a commander in northern Iraq in 2005. A 1997 book he authored is pointedly titled "Dereliction of Duty: Lyndon Johnson, Robert McNamara, the Joint Chiefs of Staff and the Lies That Led to Vietnam."

House Intelligence Committee Chairman Devin Nunes was prompt to praise McMaster's "history of questioning the status quo and infusing fresh thinking and new approaches into military affairs."

The White House said that Trump "gave full authority for McMaster to hire whatever staff he sees fit."

Trump announced the counterinsurgency strategist's appointment at his Florida estate Mar-a-Lago, ending a one-week search to replace Michael Flynn, who spent less than a month in the position before being asked to resign.

Flynn was forced to resign 13 on February, after questionable contacts with the Russian government and revelations that he lied about them to the vice president and the FBI.

Trump's first choice, retired Vice Admiral Robert Harward, turned down the role, citing "personal reasons".